docs: def get_page_numbers(current_page, num_pages):
      """Default callable for page listing.
      Produce a Digg-style pagination.
      """
  
      if current_page <= 2:
          start_page = 1
      else:
          start_page = current_page - 2
  
      if num_pages <= 4:
          end_page = num_pages
      else:
          end_page = start_page + 4
          if end_page > num_pages:
              end_page = num_pages
  
      pages = []
      if current_page != 1:
          pages.append('first')
          pages.append('previous')
      pages.extend([i for i in range(start_page, end_page + 1)])
      if current_page != num_pages:
          pages.append('next')
          pages.append('last')
      return pages